220 11865 <8DC3E474-3957-40B2-B492-D4AF2FDDD451@gmail.com> article Path: news.gmane.org!not-for-mail From: David Krauss Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: N4078: Rvalue reference overloads for value() method returns object by value Date: Fri, 11 Jul 2014 18:37:15 +0800 Lines: 35 Approved: news@gmane.org Message-ID: <8DC3E474-3957-40B2-B492-D4AF2FDDD451@gmail.com> References: <4DA018C3-2327-4F55-B7F8-7988EC7B789A@gmail.com> <1a858a77-310b-4591-aaf5-960c40d9f5fc@isocpp.org> <66AF41C1-CB37-4311-98EA-D47DBC6068DC@gmail.com> <66c38b61-7a95-4ace-b34f-2346bb334fb9@isocpp.org> <6F4B3C72-9962-48DC-8527-0C89EA1B9710@gmail.com> <35873CE5-ED8C-4C03-A6A1-E4132DECD91F@gmail.com> <335948E6-8140-4673-B958-930356A52070@gmail.com> <76ACA175-5A44-4BE8-B49F-BAC6DA65E6B1@gmail.com> <4D3852AD-1AEB-44BA-941C-D645BAD19405@gmail.com> <6a4b6425-1167-40c1-acd8-3945c8cd4c74@isocpp.org> <13DD0D7A-A146-4667-9F30-6FB3739CDBE0@gmail.com> <6B925FF7-2940-44C7-BF1D-13209A703BA2@gmail.com> <944C9C01-865B-4215-8C91-95F01AEA256E@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1405075055 19758 80.91.229.3 (11 Jul 2014 10:37:35 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 11 Jul 2014 10:37:35 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCW25A7E3QCRBYX472OQKGQEC546A5A@isocpp.org Fri Jul 11 12:37:26 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-oa0-f69.google.com ([209.85.219.69]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1X5YCj-0005yX-Jh for gclcip-std-proposals@m.gmane.org; Fri, 11 Jul 2014 12:37:25 +0200 Original-Received: by mail-oa0-f69.google.com with SMTP id j17sf4447936oag.8 for ; Fri, 11 Jul 2014 03:37:23 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date :message-id:references:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe:content-type:content-transfer-encoding; bh=SJvwCnvbviOD+JZaVR/TJM1ijMX+BxO38UV1ubgxDks=; b=EAqTiWv9CEizwN+kTCLSvvUwVDwBd4rcCICCibkoUy/pu7WUmytXoeMUdyrPQkYdmA RtJd5SMk00doDLL9elYQyY4hyYs4Xv7FZfxwODT3LEDAgCkH9X4P6tWc5N+YoGtmrXFs X/fNI/dN9KLhtigpVCcQbEXTfm8Ah7P9I/U5D0S9qYAVdJUfr0E7umJgLCV88lNbPmzK HPsu1/hsyEGK3C0V6tkGhefNpaG8FazEeoQsglt6yrq+28RqqCIriammU2asRE7MfZlD 2wh0otDXMgShunasSD4BB9LtQtRK9TnpnBR5gOUnHf80CqH9VBgxRCg5RVCQhAaFTba4 el9Q== X-Gm-Message-State: ALoCoQk3h1CwTJQKzIhqkYN8dc6YS9tF3l7MhANkQ1fOu/cWUQb4pOAGHA+wcbN2S2+H2eTJ3LJL X-Received: by 10.182.213.135 with SMTP id ns7mr23874291obc.46.1405075043441; Fri, 11 Jul 2014 03:37:23 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.115.35 with SMTP id jl3ls285094igb.44.gmail; Fri, 11 Jul 2014 03:37:22 -0700 (PDT) X-Received: by 10.42.214.207 with SMTP id hb15mr3686333icb.30.1405075042640; Fri, 11 Jul 2014 03:37:22 -0700 (PDT) Original-Received: from mail-ie0-x231.google.com (mail-ie0-x231.google.com [2607:f8b0:4001:c03::231]) by mx.google.com with ESMTPS id op10si2657682igb.59.2014.07.11.03.37.22 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 11 Jul 2014 03:37:22 -0700 (PDT) Received-SPF: pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:4001:c03::231 as permitted sender) client-ip=2607:f8b0:4001:c03::231; Original-Received: by mail-ie0-f177.google.com with SMTP id at20so692706iec.8 for ; Fri, 11 Jul 2014 03:37:22 -0700 (PDT) X-Received: by 10.50.60.41 with SMTP id e9mr3284451igr.11.1405075042168; Fri, 11 Jul 2014 03:37:22 -0700 (PDT) Original-Received: from [172.20.10.2] ([121.54.54.152]) by mx.google.com with ESMTPSA id l9sm1516322ige.2.2014.07.11.03.37.20 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 11 Jul 2014 03:37:21 -0700 (PDT) In-Reply-To: X-Mailer: Apple Mail (2.1878.6) X-Original-Sender: potswa@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:4001:c03::231 as permitted sender) smtp.mail=potswa@gmail.com; dkim=pass header.i=@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:11865 Archived-At: On 2014-07-11, at 6:33 PM, Olaf van der Spek wrote: > On Fri, Jul 11, 2014 at 12:31 PM, David Krauss wrote: >>> So the problem is basically the auto&&? You're looking for something >>> that won't deduce to a xvalue.. >>=20 >> Categories aren't deduced, types are. An named auto && is not an xvalue. I meant, named T &&. > But the problem is still the auto&& isn't it? You're looking for > something that'll copy instead of becoming a dangling reference. Yes, the problem is dangling references. I think they're an avoidable libra= ry design choice, and they don't add fundamental capability. If you know th= at an xvalue would be safe, and you can obtain an lvalue reference, then yo= u can convert the xvalue to an lvalue. The metaprogramming behind that tran= sfer is the big question. But, I've said my peace as for this thread, and I hope the discussion can c= ontinue with proper papers, etc. --=20 ---=20 You received this message because you are subscribed to the Google Groups "= ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposa= ls/. .